传统感光胶片上的化学药剂是（）A、卤化银 B、卤化铝 C、卤化铁 D、氧化银

火车轨道在转弯处外轨高于内轨，且高度差由转弯半径与火车速度确定．若在某转弯处规定行驶速度为v，则下列说法中正确的是（　　）

①当以v的速度通过此弯路时，火车重力与轨道面支持力的合力提供向心力

②当以v的速度通过此弯路时，火车重力、轨道面支持力和外轨对轮缘弹力的合力提供向心力

③当速度大于v时，轮缘挤压外轨

④当速度小于v时，轮缘挤压外轨．

A．①③

B．①④

C．②③

D．②④

在右面的算式的○里填上适当的运算符号．[50.8-（20+9.6○0.4）]×5=34．

A smart phone (智能手机) is a mobile phone built on a mobile operating system, with more advanced computing abilities than a common phone. The first smart phones enabled the users to send and receive emails. Later models added the function of portable media players, pocket video cameras, and GPS navigation (导航) units to form one multi-use device. Many modern smart phones also include touchscreens and web browsers (浏览器) that display web pages.

A recent report says we spend an average of two hours and 40 minutes each day looking at a smart phone. That doesn’t mean making calls, but playing phone games and browsing the Web.

Nowadays we always find people checking emails in a restaurant, taking a picture of the food when it arrives, or checking a message during a conversation instead of traditional communication. It’s no secret that our lives are being affected by our smart phones obsession.

However, this phenomenon has never been presented so vividly as in the short YouTube film I Forgot My Phone. Despite only being online for a few days, it's already been viewed more than 10.5 million times. Whether it will be screened in the cinema remains to be seen.

Ironically, YouTube’s data show that the site gets a billion views per day from mobile devices, so a lot of those people watched it on their phones.

The short film, written by and starring actress Charlene Deguzman, shows groups of people in various social situations, the majority of whom are absorbed in their phones instead of the world around them. To a certain extent, we all do it.

小题1:People prefer a smart phone to a common one, because the latter only can help us ______.

A．check emails

B．send messages

C．find the destination

D．watch a video小题2:The underlined word “obsession” in the third paragraph most probably means “______”.

A．devotion

B．contribution

C．addiction

D．emotion小题3:Which of the following is right?

A．People spend as average of two hours and 40 minutes each day using smart phones.

B．The film hasn’t been put on in the cinema.

C．The film is written by an actor named Charlene Deguzman.

D．The film has already been viewed more than 105 million times in the first few days.小题4:When the writer mentions the number of people watching the film from mobile devices in the fifth paragraph, he mainly feels ______.

A．encouraged

B．depressed

C．proud

D．satisfied

男性，50岁，胆石症病史10余年，1周前曾呕血、便血1次，保守治疗后好转，2小时前突发上腹部剧烈绞痛，出冷汗，伴呕血、便血。查体：巩膜黄染，血压80/60mmHg，脉搏100次/min。腹胀，肠鸣音活跃。

结合病史和最可能的诊断，此次经非手术治疗后患者的呕血、便血会呈周期性复发．间隔期一般为

A．1～2周

B．1～2个月

C．5～6个月

D．1～2年

光纤和光缆如何分类？G.652、G.653、G.654、G.655特性有何不同？